EP2279341B1 - Device for reducing noise generated by an aircraft jet engine with curved ducts - Google Patents

Description

The invention relates to an aircraft reactor according to claim 1.

In known manner, an aircraft reactor is in the form of a nacelle in the center of which is positioned a turbomachine.

This nacelle is intended to be mounted under the wing of an aircraft through a reactor mast.

The turbomachine is composed of a gas generator which drives a fan mounted on the shaft of the gas generator, upstream of the latter in the longitudinal direction of the reactor nacelle.

The airflow that passes longitudinally through the nacelle penetrates part of the gas generator and participates in the combustion.

This stream is called primary stream and is ejected at the output of the generator.

The part of the air flow entering the nacelle and which does not pass through the gas generator is driven by the fan.

This flow, called secondary flow, flows in an annular passage, concentrically with respect to the primary flow. This passage is formed between an outer longitudinal wall (nacelle wall) and an inner longitudinal wall surrounding the gas generator.

The secondary flow is ejected from the nacelle at the downstream end of the outer wall thereof in the substantially longitudinal direction of the reactor.

The inner wall surrounding the gas generator also defines with an inner longitudinal member an annular passage through which flows the primary flow.

This flow is ejected at the downstream end of the inner wall which surrounds the gas generator.

During the takeoff phases, the gas flow that is ejected (primary and secondary flows) adopts very high speeds. At these speeds, the meeting of the flow ejected with the surrounding air, as well as the meeting of the primary flow and secondary flow generate a significant noise.

We know from the international application WO2002 / 013243 a fluidic device for reducing the noise generated by an aircraft reactor.

This device comprises several pairs of conduits emerging at the outlet of a nozzle of the jet engine ejecting a propellant jet and which are distributed at the periphery of this nozzle.

The ducts of each pair each eject an air jet and are arranged convergently with respect to each other to output a triangle of interaction of the air jets.

The angle of convergence of the ducts is between 40 and 70 °,

In addition, the ducts are inclined at a so-called penetration angle towards the longitudinal axis of the reactor along which the flow of gas is ejected.

This angle allows the jets ejected by the ducts to penetrate inside the flow of gas leaving the reactor nozzle.

This angle corresponds, for example, to the inclination on the longitudinal axis of the trailing edge of the downstream end of the nozzle, insofar as the ducts are arranged in their end part along this inclined edge.

The document FR 2 901 321 describes a method for homogenizing the air leaving the turbojet to lower the noise generated. An aircraft engine nacelle comprises in a downstream section of the nacelle several diffusers connected to an air distribution duct, designed to have a shape adapted to the constricted lines of the downstream of the nacelle.

The document "Significant Improvements on Jet Noise Reduction by Chevron-Microjet Combination (AIAA 2007-3598)" describes the combination of two methods of noise reduction including, on the one hand, micro-ducts emitting fluid jets and, on the other hand, mechanical chevrons. These micro-ducts are positioned at an angle of penetration of 60 ° with respect to the longitudinal axis of the nozzle.

The document FR 2,892,152 describes a device for attenuating the emission noise on a turbine engine. Housings arranged at the periphery of the rear part of the hood of a blower behave like ducts provided with an outlet orifice. The covers are arranged to eject jets parallel to each other at a skid angle formed with the longitudinal axis of the system.

The Applicant has found, however, that by increasing the value of the penetration angle the jets interact more with the flow of gas ejected from the nozzle, which contributes to further reduce the noise generated. This effect has In particular, it has been observed for angles of the order of several tens of degrees.

However, the presence of the beveled trailing edge of the nozzle (exit lip) makes it difficult to choose the angle of penetration and in particular its increase.

It would therefore be interesting to be able to easily adapt the angle of penetration of the conduits to the desired application taking into account the environmental constraints (example: beveled trailing edge of the nozzle).

In addition, when it is desired to integrate the ducts in the thickness of the wall of the nozzle, it is difficult to select the angle of penetration that is desired given these integration constraints.

This is all the more true if we want to reduce the space generated by the ducts.

Furthermore, it could also be advantageous to have, in association with the downstream end of the reactor nozzle, a duct configuration making it possible to orient the jet leaving the duct in a controlled manner, in a chosen direction, and a small footprint.

The present invention aims to remedy at least one of the aforementioned drawbacks and / or to achieve one of the aforementioned aims by proposing an aircraft reactor comprising a wall surrounding a first gas stream which is ejected at a downstream end of the wall following a longitudinal axis XX ', a second flow of gas flowing outside the wall in the direction of ejection of the first gas flow, at least one duct arranged at the periphery of the downstream end of the wall and which is capable of ejecting a jet of fluid intended to interact with one and / or the other gas flow, said at least one duct comprising an end portion provided at its free end with an outlet orifice through which the jet of fluid is ejected, characterized in that the terminal portion comprises successively a first portion of rectilinear conduit aligned along a said median axis and a second portion of conduit forming a bend relative to the rectilinear portion, the second portion having a free end provided with the outlet orifice and is sufficiently close to the median axis of the first portion so as to give the end portion a reduced bulk in the direction of formation of the bend.

The second portion forming a bend of small radial extension (transverse to the central axis) makes it possible to easily and in a controlled manner to the jet of fluid coming from the outlet orifice the desired orientation (effective exit angle) despite limited space available.

Furthermore, this short bend formed in the end portion of the duct or conduits can effectively control the jet of fluid that is ejected. The bend provides proper jet guidance by providing velocity distributions at the outlet of the orifice which have maximum velocities and parallel flow.

The control would indeed be less effective if the elbow was extended by a straight portion over a distance too large and, moreover, the congestion generated would be increased.

By controlling the distance between the outlet orifice and the median axis of the rectilinear portion, the radial space of the duct or conduits is mastered.

This makes it easy to associate the duct or ducts to the reactor wall despite numerous penalizing constraints (space, environment, etc.).

The outlet orifice or the exit face of the duct with this orifice must not be at a distance from the axis greater than twice the value of the radius of the first portion (or its half-width or half-height) to meet a reasonable size. The distance is taken between the axis and the middle of the orifice.

Note that the second flow of gas may be the surrounding air when the first flow is the secondary flow or correspond to the secondary flow when the first flow is the primary flow.

According to one feature, the second portion forming a bend has a continuous curvature, that is to say that the outer radius of curvature of the bend is substantially constant over its entire extension, since the upstream end of the bend in contact with the rectilinear portion until at the downstream end of the elbow.

In other words, the elbow does not have outside of sudden variation of radius of curvature.

Such a curved portion makes it possible to produce a fluid jet that is particularly effective in attenuating the noise generated by the first flow of gas leaving the reactor.

This can be explained by the fact that the flow of fluid in the bend is gradually and controllably deflected from its initial trajectory given by the median axis to reach its final orientation.

Note also that the radius of curvature may be larger or smaller depending on the intended application.

Thus, a small radius of curvature will confer an axial size (in a direction parallel to that of the central axis) reduced in addition to reduced radial size.

A large radius of curvature will provide greater axial extension, while maintaining a reduced radial size.

The progressive elbow is formed for example by bending a rectilinear conduit section.

According to another characteristic, the elbow is formed by a straight portion of duct connected to the straight portion at a connecting angle.

Thus, the elbow has on the outside a sudden variation of radius of curvature.

The flow of fluid internal to the conduit is therefore deflected by the bend abruptly, which induces in the flow and in the jet formed disturbances. The sudden deviation induces overspeeds in the inner part of the elbow, probably induced by detachments inside the ducts. These Overspeeds can be favorable to longitudinal eddy generations and amplify the effects of jets.

Note that the right portion may be more or less truncated on one of its sides in order to be easily connected to the first straight portion and without increasing the size unreasonably.

Such a truncated portion takes, for example, a wedge or triangle shape in a view in a plane containing the longitudinal axis XX 'of the reactor and the median axis.

The right portion can be assembled in different ways to the first portion, in particular by welding.

According to one characteristic, the outlet orifice is disposed in a plane that is substantially tangential to the first rectilinear conduit portion.

The orifice is thus arranged in the axial extension of the first portion (flush with the duct portion), which makes it possible to control the deflection of the flow and not to increase the overall radial size of the assembly.

It will be noted that the outlet orifice may be inclined with respect to the median axis without increasing the bulk.

According to one characteristic, said at least one duct is disposed in the thickness of the reactor wall (dimension of the wall taken radially or transversely with respect to the longitudinal axis XX ').

This arrangement is made possible by the small thickness or radial extension of the duct or conduits thus configured.

According to one characteristic, the second portion forming a bend gives said at least one duct an inclination towards the longitudinal axis XX 'of the reactor at an angle of penetration.

The choice of the orientation of the outlet orifice relative to the median axis of the first portion makes it possible to give the duct (s) the desired penetration angle.

This angle appears in a projection view in a plane containing the longitudinal axis and the median axis.

According to one characteristic, the second portion forming a bend gives said at least one duct an inclination relative to the longitudinal axis XX 'of the reactor at a wiping angle.

The choice of the orientation of the outlet orifice with respect to the median axis of the first portion makes it possible to give the duct (s) the desired slip angle.

According to one feature, the second portion forming a bend gives said at least one duct a double inclination at a penetration angle and at a skid angle.

For a given orientation of the median axis of the first portion (the latter may, for example, already be oriented according to a penetration angle and / or a slip angle), the elbow confers, by its orientation vis-à-vis screw of the median axis, both the final penetration angle and the desired final slip angle.

It is thus conceivable that the elbow makes it possible to precisely adjust the direction of the jet of fluid generated by the end portion of the duct or ducts.

According to one characteristic, the ducts are integrated in the wall, which makes it possible to reduce the space requirement.

According to one characteristic, the downstream end of the wall comprises a plurality of chevrons distributed around the periphery thereof in order to form a mechanical acoustic attenuation device.

The rafters interact with the flow of gas from the downstream end where they are arranged, giving rise to vortices that propagate along the flow (in the longitudinal direction of the reactor) and contribute to reducing the noise.

When the fluid ejection ducts are arranged in relation to the downstream end of the wall, the rafters may be arranged at the same end to enhance the attenuation effect of the noise generated by the reactor.

Alternatively, the rafters may be provided at another downstream end of the wall that surrounds the outlet of another stream ejected from the reactor.

According to another variant, the fluid ejection ducts and the rafters may be integrated at the same downstream end of the wall, while another downstream end of the wall surrounding the outlet of another flow ejected from the reactor may also be equipped. single rafters or single ducts or rafters in cooperation with ducts.

According to one characteristic, the ducts are associated with chevrons which give the downstream end of the wall a serrated shape comprising a succession of peaks and valleys.

The fluid jet leaving each duct is associated with the longitudinal vortex generated at the associated chevron and thus reinforces its noise-reducing action.

• d'étendre l'impact spatial des chevrons, c'est-à-dire à effet identique, d'avoir des chevrons plus courts (moins pénalisants en croisière) ou à taille de chevron identique, d'en augmenter l'efficacité,
• de créer des effets spatiaux nouveaux dans la mesure où les jets interagissent avec le jet propulsif en différentes positions à partir du bord de fuite ; ceci permet donc d'avoir différents gradients de pression, ce qui peut être favorable à l'action des jets en amplifiant par exemple leur pénétration.

The combination of fluid jets with the rafters allows:

• to extend the spatial impact of chevrons, ie with the same effect, to have shorter chevrons (less penalizing in cruising) or identical chevron size, to increase their effectiveness,
• to create new spatial effects insofar as the jets interact with the propulsive jet in different positions from the trailing edge; this allows to have different pressure gradients, which can be favorable to the action of the jets amplifying for example their penetration.

The invention also relates to an aircraft comprising at least one reactor according to the brief description mentioned above.

• la figure 1 est une vue générale schématique en coupe longitudinale d'un réacteur d'aéronef dans laquelle seule la partie supérieure du capot de soufflante a été enlevée;
• la figure 2 est une vue schématique en perspective d'une extrémité aval de paroi de nacelle équipée selon un premier mode de réalisation de l'invention ;
• les figures 3a et 3b illustrent de façon schématique un exemple de réalisation d'une partie terminale de conduit selon l'invention ;
• les figures 3c et 3d illustrent de façon schématique différentes orientations spatiales de la partie terminale de conduit représentée sur les figures 3a et 3b ;
• la figure 3e illustre de façon schématique un agencement possible d'une partie terminale de conduit sur le bord de fuite de la tuyère de réacteur ;
• la figure 3f illustre de façon schématique l'intégration d'une partie terminale de conduit à l'intérieur d'une paroi de tuyère de réacteur ;
• la figure 3g illustre une variante de réalisation de la partie terminale de conduit représentée sur la figure 3a ;
• la figure 4a illustre de façon schématique une partie terminale de conduit selon un autre mode de réalisation de l'invention ;
• la figure 4b illustre une partie terminale de conduit selon une variante de réalisation de la partie terminale de conduit de la figure 4a ;
• la figure 5 illustre un autre mode de réalisation de l'invention dans lequel des conduits coudés sont associés à des chevrons.

Other characteristics and advantages will become apparent from the following description, given solely by way of nonlimiting example and with reference to the appended drawings, in which:

• the figure 1 is a schematic longitudinal sectional view of an aircraft reactor in which only the upper part of the fan cowl has been removed;
• the figure 2 is a schematic perspective view of a nacelle wall downstream end equipped according to a first embodiment of the invention;
• the Figures 3a and 3b illustrate schematically an embodiment of an end portion of conduit according to the invention;
• the Figures 3c and 3d schematically illustrate different spatial orientations of the terminal part of the duct shown on the Figures 3a and 3b ;
• the figure 3e schematically illustrates a possible arrangement of an end portion of conduit on the trailing edge of the reactor nozzle;
• the figure 3f schematically illustrates the integration of an end portion of conduit within a reactor nozzle wall;
• the figure 3g illustrates an alternative embodiment of the terminal portion of the duct shown in FIG. figure 3a ;
• the figure 4a schematically illustrates an end portion of conduit according to another embodiment of the invention;
• the figure 4b illustrates an end portion of conduit according to an embodiment variant of the terminal portion of the conduit of the figure 4a ;
• the figure 5 illustrates another embodiment of the invention in which bent ducts are associated with rafters.

As represented in figure 1 and designated by the general reference number 2, an aircraft engine nacelle envelopes a turbomachine 4 and is mounted under a wing 6 of an aircraft in a known manner using a reactor mast 8.

The turbomachine 4 comprises a gas generator which drives a fan 10 mounted on the generator shaft, upstream of the latter in the longitudinal direction of the reactor nacelle.

The nacelle has a symmetry of revolution about the longitudinal axis XX '.

The air flow 12 which enters the nacelle, passes longitudinally thereof, penetrates in part into the gas generator 4 and participates in the combustion.

The hot propulsive flow 14 ejected at the output of the generator is called primary flow.

The portion of the air flow 12 entering the nacelle and which does not pass through the gas generator is driven by the fan 10.

This cold propulsive flow 16, called secondary flow, flows in an annular passage 18 arranged concentrically with respect to the primary flow 14.

This passage 18 is formed between an outer longitudinal wall 20 (nacelle cover) and an inner longitudinal wall 22 (engine cover) surrounding the gas generator.

The secondary flow 16 is ejected from the nacelle at the downstream end 20a of the outer wall 20, substantially in the longitudinal direction of the reactor.

The inner longitudinal wall 22 defining the outer casing of the gas generator defines with the central longitudinal portion 24 constituting the core of the motor another annular passage 26 through which flows the primary flow 14.

This flow is more particularly ejected at the downstream end 22a of the inner wall 22.

A fluidic device for reducing the sound level of the reactor according to the invention is applied to the reactor nacelle 2 of the figure 1 .

This device is for example arranged in relation with the substantially cylindrical outer wall (outer cover) of the nacelle and which surrounds the annular passage 18 through which the secondary flow 16 is ejected.

It can also be arranged in relation to the inner wall 22 (inner cover) of the nacelle surrounding the turbomachine 4 and at the end of which the primary flow 14 is ejected.

It will be noted that a fluidic device may be provided at one and / or the other of the two concentric walls (outer and inner covers).

More particularly, the fluidic device according to the invention is associated with a so-called downstream end 20a and / or 22a of the wall concerned, at the trailing edge thereof (also called the exit lip).

The fluidic device according to the invention is capable of generating, on command, a disturbance of the flow immediately downstream of the downstream end of the wall at the outer periphery of the flow (primary or secondary) ejected by this end.

It will be noted that the fluidic device according to the invention can be added simply to an existing reactor nacelle nozzle, without calling into question the entire design and manufacture of the latter.

Fluidic disturbance alters the way the ejected flow meets the external flow (which is the air surrounding the nacelle when the ejected flow is the secondary flow) and interacts with the ejected flow to form vortices that propagate longitudinally to the flow. downstream.

The aforementioned phenomenon is intended to reduce the noise generated by the engine thus equipped, especially during the take-off and approach phases of the aircraft.

The device according to the invention can take different embodiments and some structures of the device will be described in the following.

However, each of these structures offers the advantage of effectively reducing the noise generated by a large reactor (for example, diameter of the outer ring of the nacelle of the order of one meter).

On the figure 2 , a plurality of fluidic devices according to a first embodiment of the invention equip one of the two walls of nacelle represented at figure 1 and which here is referenced 30. The wall shown in FIG. figure 2 forms a nozzle in which flows a first flow (primary or secondary) which is ejected at the downstream end 30a of the wall in the direction given by the axis XX '.

In this embodiment, the fluidic devices 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62 are, for example, regularly distributed at the outer periphery. the downstream end 30a of the wall, at the output ring, and are spaced from each other.

Each device takes the form of a conduit which is able to eject a jet of fluid at the downstream end 30a of the wall. According to the orientation given to the jet by the conduit, the jet interacts with the first flow or the second external flow flowing outwardly along the wall 30 or with both flows if the jet is directed to the interface of the two streams.

Alternatively, some conduits may be directed to the first stream while others are directed to the second stream.

Note that in other embodiments, the devices may be integrated in the thickness of the wall or on the inner face thereof (inner periphery) which is in contact with the flow of the first (primary) flow. or secondary) ejected.

It should also be noted that the devices may be distributed differently depending on the azimuth.

This allows for example to take into account the presence of the reactor mast 8 which modifies the flow.

This non-homogeneous arrangement also makes it possible to take into account the directivity of the noise and the regulatory noise constraints with respect to the neighborhood. It is indeed preferable to limit the radiated noise towards the ground rather than the noise radiated towards the sky.

In the application shown on the figure 2 the conduits of the devices are associated in pairs 64, 66, 68, 70, 72, 74, 76, 78 and converge towards each other within the same pair of conduits as described in the international patent application W02002 / 013243 .

Thus, the jets produced by the ducts of the same pair converge and form a fluidic triangle of interaction.

The inclination of the ducts gives the jets which are derived a tangential velocity component which, because of the interaction with the jet propulsion, causes a rotation of the jets on themselves, in the opposite direction for two convergent jets. This rotation can be promoted by means such as those mentioned above. Moreover, the above-mentioned convergence angle causes the two converging jets to meet at a short distance, of the order of a quarter of the diameter of the nozzle.

When the embodiment concerns the crown separating the cold external jet (secondary flow) and the hot central jet (primary flow), the rotation of the jets causes cold external air inside the propulsive jet between the convergent jets, from the hot air coming out on the outside outside the jets.

This results in a homogenization of the temperatures right out of the nozzle, which can contribute to the reduction of the noise generated by this nozzle. There is also a heat shield effect, which is also favorable for the reduction of radiated noise.

In the example shown in figure 2 the pairs of conduits are distributed so that the converging conduit in one direction directly juxtaposes the conduit of the adjacent pair and has an opposite convergence.

However, the spacing between the tubes of the same pair and the spacing of the adjacent tubes of two different pairs will be a function of the number of tubes to equip the nozzle and the diameter of the latter. Indeed, in the illustrated example, the nozzle comprises eight pairs (64, ..., 78) of tubings. It is of course obvious that this is an exemplary embodiment given by way of illustration, the number of pairs of tubings can be lower or higher. The number of pairs of tubings attached to the nozzle will be a function, in particular, of the size of the reactor, but also of the noise nuisance of the reactors.

Thus, in order to reduce the noise associated with the jet engines of the reactors at the time of the takeoff phase or the approach phase of the aircraft, a blow of compressed air is initiated through the air supply ducts. to the pipes distributed at the outlet ring of said nozzle. The crown concerned can be either that (inner crown) separating the hot flow (primary flow) and the cold flow (secondary flow), or that separating the flow cold (secondary flow) and ambient air (crown of the nacelle). By the positioning of the pipes at the outlet ring and their distribution, the compressed air jets are propelled out of the pipes according to incidences of convergence and penetration, thus disturbing the propulsive jet according to fluid interaction triangles. in the direction of flow.

The air jets are controlled jets. Connected to the high pressure part of the reactor, their supply is made effective only in the phases where the control is necessary (generally during the take-off or landing phases). Outside these phases, the fluidic devices according to the invention are rendered inactive by simply cutting off the supply of compressed air. The aircraft thus equipped, has no penalty in terms of drag or loss of thrust.

Note that the jets can be activated independently of each other, thus providing a particularly flexible ejected flow disturbance system. Thus, it can be envisaged a partial activation of said jets: actuation of jets positioned on the top, bottom, right or left of said nozzle, thus changing the directivity of noise emissions.

According to another variant, the control jets can be actuated unsteady in order to reduce the flow rates of the control jets or to improve the performance of the control.

The constitution of one of these fluidic devices will now be described by taking the device 32 as an example, all the other devices being identical thereto in this embodiment.

The device 32 comprises a conduit 80 which is connected, for example, via a fluid supply pipe, here air (the tubing is not shown), to the high pressure part of the reactor.

The duct 80 has an end portion 82 which is provided at its free end with an outlet orifice 84. Thus fed with compressed air, the duct carries this air to its outlet orifice where it is ejected in the form of 'a jet.

In the example shown on the figure 2 the orifice is circular in shape and the jet adopts a circular diameter. However, other configurations of outlets are possible.

The figure 3a illustrates the end portion 82 of the conduit 80 in a plane perpendicular to the plane in which the outlet port 84 is arranged.

The plane of the outlet orifice may adopt various orientations in the space and the longitudinal axis XX 'is not necessarily included in this plane.

The figure 3b represents in view from below this end portion and shows the passage section of the outlet orifice 84 seen from the front.

As shown on the figure 3a , the end portion 82 more particularly comprises, successively from upstream to downstream, a first portion of rectilinear conduit 86 and a second portion of conduit 88 forming a bend relative to the first portion.

The first portion is aligned along an axis a ₁ , called the median axis, which, in the case of a cylindrical portion, coincides with the axis of revolution of the cylinder.

When the duct portion is not cylindrical but takes another form (example: flattened or flared portion to produce a substantially plane jet), this axis is placed in a median plane of the portion (the median plane is perpendicular to the plane of the figure 3a ).

The flow of fluid flowing in the first portion is directed along this axis.

The second portion 88 forms a bend to deflect the flow of its axial trajectory. This elbow extends a short distance from a downstream end 86a of the first portion to the free end of the second portion which is provided with the outlet orifice 84.

The end portion 82 thus bent is formed from a rectilinear conduit portion of which an end portion is bent in the desired direction.

In this way, a continuous curvature is given to the end portion of the duct 80.

The free end of the curved end portion is then bevelled to form the outlet orifice 84 with the desired angular orientation relative to the axis a ₁ and at a given distance from this axis.

In the example shown on the figure 3a , the orifice 84 is located in a plane P1 which is perpendicular to the plane in which the elbow extends (plane of the figure). The plane P1 is parallel to a plane P2 containing the axis a ₁ and which is perpendicular to the plane in which the elbow extends.

Thus, the free end of the end portion has been cut obliquely with respect to the extension direction in order to reduce the bulk generated by the curvature.

In addition, the outlet orifice is placed at a short distance from the axis a ₁ to reduce the bulk of the end portion in the extension direction of the elbow.

The distance is taken between the center of the outlet orifice and the axis a ₁ .

This distance is generally between one and two radii of the tube forming the rectilinear portion 86. For non-cylindrical conduits, the reference dimension will be an equivalent dimension of the transverse half-width type ...

The arrow F gives, at the outlet of the orifice, the direction in which the flow of fluid has been deflected by the bend.

This direction is parallel to the direction of extension of the outer wall 88a of the elbow.

Note that the curvature of the elbow may be more or less pronounced, that is to say that the radius of curvature R may be low value or high value depending on the intended application and, in particular, depending on the length of which has to associate the elbow to the wall of the reactor.

The control of the curvature makes it possible to choose the direction of the flow and therefore of the jet formed at the outlet orifice.

Thus, depending on the direction in which the elbow is formed in space, the curvature makes it possible to give the end portion 82 of the duct a skid angle, a penetration angle or a combination of these two types of angle.

The end portion 82 of the duct 80 and each of the ducts of the figure 2 is curved in a direction which gives the ducts both a skid angle d with respect to the longitudinal axis XX '(see this angle on the figure 3c ) and a penetration angle p in the direction of the axis XX '(see this angle on the figure 3d ). The skid angle makes it possible to converge the two ducts of the same pair towards each other. The penetration angle allows, for its part, to tilt the jet from the duct on the axis XX 'so that it penetrates (more or less depending on the selected inclination) in the gas flow ejected by the nozzle.

It should be noted that the ducts can be arranged following the inclination of the trailing edge, as shown schematically on the figure 3e , which already provides a first angle of penetration p1 to which is added the angle conferred by the elbow.

It should also be noted that the penetration angle may vary from one conduit to the other or for some ducts only, in order to locally vary the orientation of the jet according to specific circumstances (bulk, directivity of noise. ..).

Alternatively, the conduits may be arranged parallel to the direction of extension of the reactor wall, without penetration angle, for example being arranged in the thickness of the reactor wall (see FIG. figure 3f ).

On the figure 3f the end portion 85 of the duct, which has been extended so as to open axially beyond the downstream end 30a of the wall, has also been represented in a variant (in dashed lines), without, however, giving a radial space greater than that of the terminal part 82.

Alternatively, the bend of the end portion 82 of the conduit 80 of the figure 3a can be formed in a direction such that the plane containing the outlet orifice 84 passes through the longitudinal axis XX 'of the reactor (direction perpendicular to the axis XX' and tangent to the periphery of the wall).

Thus, the orientation F given to the jet of fluid from the duct will correspond only to a slip angle with respect to the axis XX '.

According to another variant, the bend can be formed solely by extending towards the axis XX 'so that the orientation F of the fluid jet corresponds only to a penetration angle.

As shown on the figure 3a other orientations of exit orifices may be envisaged such as that given by the orifice 90 (in dotted lines) which is closer to the axis a ₁ , which reduces the axial size of the elbow.

The orifices 92 and 94 are other examples showing bends even shorter and therefore smaller overall size.

Note that the actual deflection angle is not exactly the geometrical exit angle of the duct. In addition, the shorter the bends, the smaller the angle of exit relative to the geometric angle.

The continuous shape of the curvature makes it possible to produce a deflected fluid jet by ensuring an excess speed in the external part of the curvature. This Speeding is conducive to the creation of longitudinal eddies that have a beneficial role in acoustic attenuation.

The figure 3g illustrates an alternative embodiment in which the outlet orifice 96 is formed flush with the free end of the elbow once cut, and is disposed in a plane P3 parallel to the plane P1 of the figure 3a and which tangents the outer wall of the first rectilinear portion 86.

The outlet orifice thus shaped is closer to the axis a ₁ than the orifice 84 of the figure 3a and thus provides a great compactness to the duct (the orifice is part of the outer envelope defined by the duct and therefore in the space generated by it), while allowing to direct the flow of fluid in a controlled manner .

It will be noted that the outlet orifice may alternatively be arranged in an oblique plane with respect to the plane P3, such as the orifice 98, to further shorten the elbow and thus the axial size of the latter.

The Figures 4a and 4b illustrate two variants of a same embodiment of the invention in which the second portion of conduit of the end portion is connected to the first straight portion forming a bend at a sharp angle relative thereto and which extends on a short distance.

As shown on the figure 4a , the end portion 100 of the duct comprises a first portion of rectilinear duct 102 of median axis a ₁ and a second duct portion 104 which comprises a straight portion connected to the first portion at a plane of joint or oblique connection 106. The assembly of the two portions is carried out for example by welding.

It will be noted that before joining the two portions, the first portion 102 is bevelled at its free end to provide the beveled shape of the joint plane 106.

The second rectilinear portion is also cut, for example in the form of a wedge (in profile view), in order to give it the very shortened shape of the figure 4a .

However, the second rectilinear portion may be longer as illustrated by the dotted lines 108 and 110 on the figure 4a .

The outlet orifice of each of these second portions, namely the orifice 112, 114, 116 is thus arranged at a greater and greater distance from the axis a ₁ without, however, significantly penalizing the overall bulk. duct thus configured.

The same peculiarities and advantages as those described with reference to Figures 3a to 3g also apply here with the exception of the impact of the elbow on the formation of the jet and its characteristics and they will not be recalled.

Indeed, the brutal nature of the elbow induces different effects on the internal flow of the duct and the formation of the jet.

In particular, excess fluid velocity induced by curvature occurs here in the inner portion of the curvature.

It will be noted that the portion of the outlet orifice situated on the outer edge of the elbow at its outer tip, and which is referenced 112a for the orifice 112, 114a for the orifice 114 and 116a for the orifice 116, makes it possible to Locally fix the fluid detachments.

Thus, the formed jet is less diffuse and has a longer life and therefore increased efficiency.

The orientations in the space of the outlets are all identical on the figure 4a but may of course vary, as has been explained with reference to Figures 3a to 3g to provide different types of angles (skid angle, penetration angle, angle having a skid angle component and a penetration angle component) to the thus bent conduit.

The figure 4b illustrates an alternative embodiment in which the second conduit portion 120 which is connected to the joint plane 106 of the free end of the first straight portion 102 also forms a corner in side view.

However, the corner is larger and the outlet port 122 of the elbow is disposed in alignment with one of the walls of the first straight portion 102, thereby tangling thereof.

In this way, the bend 120 does not extend laterally (transversely) relative to the axis a ₁ beyond the outer casing of the duct, which does not increase the radial size of the duct.

In addition, by not protruding from the radial outer casing of the duct, the elbow does not disturb the surrounding flow.

The particularities and advantages stated for the configuration of the figure 4a also apply here, except for the different positions of the outlet port relative to the axis a ₁ , and they will not be recalled.

In the above discussion with reference to Figures 2 to 4b , the outlets of the conduits have always been shown facing downward (towards the axis XX ') and / or towards the side (towards other outlets).

However, the ducts according to the invention can be bent in a direction allowing the orifices of exit, or to some of them only, to be directed towards the outside of the nozzle (radially in spacing of the axis XX ' ) and not inward to further interact with the gas flow outside the nozzle.

It will be noted that the outlet orifices of the conduits may also be inclined two by two, towards each other, within the same pair of ducts in order to converge.

It should be noted that the outlet orifices of the arrangements of the Figures 2 to 4b (Or the exit faces of the ducts which comprise these orifices) must not be too far from the median axis a ₁ of the rectilinear duct portion located upstream of the elbow.

A distance close to twice the value of the radius of the upstream duct portion (or about twice the half-width or half height in the figure, if the rectilinear portion is not cylindrical) provides a reduced space requirement and efficient fluid control of the jet.

When the outlet orifices tangent the aerodynamic lines of the conduit in its rectilinear portion (orifice 96 on the figure 3g , orifice 122 on the figure 4b ) or, at the very least, are written in its outer envelope (hole 98 on the figure 3g , orifice 122 on the figure 4a ), aerodynamic performance losses are minimized.

The outlets may extend beyond the aerodynamic lines of the rectilinear portion of the duct (beyond the lower portion of this portion in the figures) as figures 3a and 4a , remaining in an outlet plane parallel to the axis a ₁ (orifice 84) or being inclined relative to this axis (orifices 90, 114, 116).

In general, the outlets extend at most a radius (or half-width or half-height) distance from the bottom portion of the rectilinear conduit portion to maintain a small footprint. and in order not to penalize aerodynamic performance.

Note that when the orifices are oriented obliquely, their distance to the axis a1 or the lower aerodynamic line of the duct is taken relative to their center.

It is very schematically represented on the figure 5 the arrangement of two ducts 150a, 150b in connection with a chevron 152 arranged at the downstream end of the wall 30 of the nacelle in particular to amplify the effects produced by the chevron.

The downstream end comprises a plurality of successive chevrons of which only three are represented 152, 154, 156 and each chevron may be equipped with a fluidic device comprising the two ducts 150a, 150b.

In this embodiment the two ducts 150a, 150b are arranged parallel to the median of the chevron which passes through the top of the latter.

Thus, the outlets of the open ends of the ducts are located at the top 152a of the chevron (the ends of the ducts are flared at the top) and eject, on command, a jet of fluid on either side of the top.

It will be noted that other arrangements of conduits are possible in relation to the chevrons.

Thus, for example, the ducts in their rectilinear portion may be arranged along the inclined portions 152b, 152c of the chevron (these inclined portions respectively connect the top 152a of the chevron to the depressions 158, 160 separating two chevrons), their outlet orifice always being oriented. towards the outside of the chevron.

In addition, the outlets of the ducts 150a, 150b of the figure 5 can alternately be oriented towards each other instead of being back to back.

Oriented, the orifices produce jets that extend in some way the effects of rafters.

According to another variant, the outlets of other conduits may be directed on a hollow between two rafters in replacement or in addition to the arrangement of the figure 5 .

It will be noted that the different arrangements of Figures 3a to 4b can also be associated with rafters to cooperate with them.

Claims (10)

1. Aircraft jet engine, comprising
   a wall (30) surrounding a first gas stream that is ejected at a downstream end (30a) of the wall along a longitudinal axis (XX'), a second gas stream flowing outside the wall in the direction of ejection of the first gas stream,
   at least one duct (80) arranged at the periphery of the downstream end of the wall and which is able to eject a fluid jet intended to interact with one and/or the other gas stream, the said at least one duct (80) comprising a terminal part (82) provided at its free end with an outlet opening (84) through which the fluid jet is ejected,
   characterized in that the terminal part successively comprises a first straight duct portion (86) aligned along an axis referred to as median and a second duct portion (88) forming a bend in relation to the straight portion, the second portion having a free end provided with the outlet opening and is sufficiently close to the median axis (a₁) of the first portion so as to impart to the terminal part a reduced space requirement in the direction of formation of the bend, wherein the outlet opening should not be at a distance from the median axis which is longer than twice the value of the first duct portion radius, the distance being taken between the axis and the center of the opening.
2. Aircraft jet engine according to claim 1, characterized in that the second portion forming a bend has a continuous curvature.
3. Aircraft jet engine according to claim 1, characterized in that the bend is formed by an upright duct portion connected to the straight portion along a connecting angle.
4. Aircraft jet engine according to one of claims 1 to 3, characterized in that the outlet opening is disposed in a plane that is more or less tangential to the first straight duct portion.
5. Aircraft jet engine according to one of claims 1 to 4, characterized in that the said at least one duct is disposed in the thickness of the wall of the jet engine.
6. Aircraft jet engine according to one of claims 1 to 5, characterized in that the second portion forming a bend imparts to the said at least one duct a slant toward the longitudinal axis (XX") of the jet engine along a penetration angle.
7. Aircraft jet engine according to one of claims 1 to 6, characterized in that the second portion forming a bend imparts to the said at least one duct a slant in relation to the longitudinal axis (XX') of the jet engine along a lateral angle.
8. Aircraft jet engine according to claims 6 and 7, characterized in that the second portion forming a bend imparts to the said at least one duct a dual slant according to a penetration angle and according to a lateral angle.
9. Aircraft jet engine according to one of claims 1 to 8, characterized in that the ducts are associated with chevrons that impart to the downstream end of the wall a jagged shape comprising a succession of peaks and valleys.
10. Aircraft characterized in that it comprises an aircraft jet engine according to one of claims 1 to 9.

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